stage heads for 3.8

[postal]

I was told by a reputable guy that there where stage heads made for Indy 3.8 motors. That these heads have the valves spaced closer together than regular stage heads, and the valves are some times smaller. The guy will sell me a set and they seam like what I'm looking for. The part I'm confused about is that he says these heads have 2.100" intake and 1.60" exhaust valves in them. Aren't stock stage heads set up for 2.02" and 1.60" valves? How the heck can 2.100's and 1.600's fit into a 3.800" bore? Anyone out there ever run stage heads on a 3.8 and if so what do you have to look for to know which heads to buy?

TIA: Jason

 

[TurboDave]

This is a very unsophisticated answer but here goes.
2.1 + 1.6 = 3.7, so they should work.

I'm pretty sure there's still some 3.8 SII's running around so there must be an easy way. Worst comes to worse, you might only have to cut some valve reliefs in the cylinder walls, but I doubt it.
I guess I'll find this out if I decide to build up my 3.8 SII

 

[Ron Tarabori]

If they are true Indy heads be aware that there are no intakes (that I know of) available for the square port Indy head.

 

[postal]

He said the intake port demensions at the gasket are 2.375" X 1.375". That deffinately isn't square, so does that mean they are not Indy heads?

2.1 + 1.6 = 3.7, so they should work.

Even on heads that use off set rocker arms because the valve spacing has been changed (like some SBC heads) there still tends to be more than 0.100" difference between the sum of the valve diameters and the cylinder bore. What would be the minimum recommended valve to cylinder wall clearance?

Thanks for the inputs: Jason

 

[odell4o8]

heads

the indy blocks that i have had 3,900 bore, the heads that i took off the indy motors are not any different than the sets that i took off motors n/a motors, as far as ports, i had a set of heads that had square ports, kendall has them now, i sold two sets of new indy heads that had 33 cc and a 2,800 stroke crank odd fire with new rods to a guy in flordia, i had a pair of stage heads on a 3,900 bore block. no problem some indy heads, had 12mm spark plugs, i had mine changed to regular plugs thanks to dave ficus, good luck,oc,